THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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StatusStatus
Current state: DRAFT [One of "Under Discussion", "Accepted", "Rejected"] DISCARDED
Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]
JIRA: KAFKA-3294
Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).
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There are already some open-source REST proxies are available. Confluent Confluent REST Proxy got comprehensive interface.
But we would like to add REST server that many users ask for under Apache Kafka repo.
We want to add Kafka Rest Server to Kafka for the following reasons.
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content types in Content-Type and Accept headers to make the format of the data explicit. This approach is borrowed from Confluent Confluent Rest Proxy.
Supported Content Content-Types are: application/vnd.kafka.binary.v1+json, application/vnd.kafka.json.v1+json
Supported Content Content-Types are: application/vnd.kafka.binary.v1+json, application/vnd.kafka.json.v1+json
Rest server can be easily scaled by deploying multiple proxy instances. This way we can spread the load across multiple proxy instanceinstances.
Producer API
REST server accepts produce requests for specific topics or partitions. It internally uses java producer instance to write messages into Kafka.
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POST /topics/test/partitions/1 HTTP/1.1 Host:kafkarest.host.com Content-Type: application/vnd.kafka.binary.v1+json Accept: application/vnd.kafka.v1+json { "records": [ { "key": "a2V5", "value": "dmFsdWU=" }, { "value": "dmFsdWU=" } ] } |
Example response:
HTTP/1.1 200 OK Content-Type: application/vnd.kafka.v1+json { "offsets": [ { "partition": 1, "offset": 1, }, { "partition": 1, "offset": 2, } ] } |
Consumer API
Description : Create a new consumer instance in the consumer group.
POST /consumers/:group |
Parameters:
group (String) - group name
Request:
JSON Object contains name, dataformat, consumer properties.
Response:
JSON Object contains response objects.
Response includes a URL including the host since the consumer is stateful and tied to a specific REST proxy instance
Status Codes:
404 Not Found
Error Code 40401 - topic Not Found
Error Code 40402 - partition Not Found
500 Internal Server Error
Error Code 50001 - Kafka Error
Example request:
POST /consumers/group/ HTTP/1.1 Accept: application/vnd.kafka.v1+json, application/vnd.kafka+json, application/json { "name": "Instance1", "format": "binary", "auto.offset.reset": "smallest", "auto.commit.enable": "false" } |
Example response:
HTTP/1.1 200 OK Content-Type: application/vnd.kafka.v1+json { "id": "Instance1", "url": "http://kafkarest1.com/consumers/group/instances/Instance1" } |
Description : consumes a message from the specified topic on behalf of the specified consumer group
GET /consumers/:group/:instance/:topic |
Parameters:
topic (String) - topic name
group (String) - consumer group id
Instance (string) - consumer instance name
Response:
JSON Object contains response objects
Status Codes:
404 Not Found
Error Code 4040X - topic Not Found
Error Code 4040Y - group Not Found
Error Code 4040Z - instance Not Found
500 Internal Server Error
Error Code 50001 - Kafka Error
Example
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request:
GET /consumers/ |
group/ |
instance1/topic HTTP/1.1 Accept: application/vnd.kafka.binary.v1+json |
Example response:
HTTP/1.1 200 OK Content-Type: application/vnd.kafka.binary.v1+json [ { "key": "a2V5", "value": "dmFsdWU=", "partition": 1, "offset": 1, }, { "key": "a2V5", "value": "dmFsdWU=", "partition": 1, "offset": 2, } ] |
Description : Commit offsets for the consumer instance associated with group.
POST /consumers/:group/:instance/offsets |
Parameters:
group (String) - consumer group id
Instance (String) - consumer instance name
Response:
JSON Object contains response objects
Status Codes:
404 Not Found
Error Code 40401 - group Not Found
Error Code 40402 - consumer instance Not Found
500 Internal Server Error
Error Code 50001 - Kafka Error
Example request:
POST /consumers/group/instance1/offsets HTTP/1.1 Accept: application/vnd.kafka.v1+json |
Example response:
HTTP/1.1 200 OK Content-Type: application/vnd.kafka.v1+json [ { "topic": "test", "partition": 1, "committed": 100 }, { "topic": "test", "partition": 2, "committed": 200 }, { "topic": "test2", "partition": 1, "committed": 50 } ] |
GET /topics/:topic_name/partitions/:partition?offset=(int)
Description : Consume messages from one partition of the topic.
Parameters:
topic_name (String) - topic name
partition (int) - partition number
offset (int) - offset to fetch
Response:
JSON Object contains response objects
Status Codes:
404 Not Found
Error Code 40401 - topic Not Found
Error Code 40402 - partition Not Found
500 Internal Server Error
Error Code 50001 - Kafka Error
Example request:
GET /consume/test/partitions/1?offset=1 HTTP/1.1 Accept: application/vnd.kafka.binary.v1+json |
Example response:
HTTP/1.1 200 OK Content-Type: application/vnd.kafka.binary.v1+json [ { "key": "a2V5", "value": "dmFsdWU=", "partition": 1, "offset": 1, }, { "key": "a2V5", "value": "dmFsdWU=", "partition": 1, "offset": 2, } ] |
TODO
I will update required config options and response Error codes/messages.
Compatibility, Deprecation, and Migration Plan
This KIP only proposes additions. There should be no compatibility issues.
Rejected Alternatives
Make Kafka Rest Server an external third-party tool
Main Reason for this KIP is to add Rest Server to Kafka. Shipping Kafka Rest Server as part of a normal Kafka release
makes it immediately available to every user that downloads Kafka. Also helps to maintain the version compatibility
between Kafka clients and Rest Server.
Push/Stream messages to end clients:
End clients can register for the listening of events. This can be implemented used Web socket push notifications.
But This is against kafka consumer's pull model. It is good maintain Kafka consumer's semantics.